MS - They got a decent number of exclusives they showed off. I'm surprised they got Insomniac to make an Xbox One exclusive game, and Scalebound from Platinum Games looks interesting. Other than that, the Master Chief Collection looks really *Can'tSayThisOnTV*ing cool, but mainly because I *Can'tSayThisOnTV*ing loved Halo 2 back in the day.
Sony - Vita TV/PlayStation TV finally coming to the West has me super excited, since I was really close to importing one if they didn't announce anything. They showed off a lot of games with Uncharted sealing the deal at the end.
Nintendo - Nintendo shows off it's huge list of first/second party titles. I think it's safe to say they won in terms of number of exclusives with Xenoblade Chronicles X, Zelda, Smash 4, Pokemon Ruby/Sapphire, Starfox, Hyrule Warriors, Yoshi, Bayonetta 1/2, etc. They're really trying to make the Wii U appealing still, with it taking almost all of their focus this year game-wise. They still won't "win" this generation, but since they're selling refurb Wii U Deluxes w/ Nintendo Land for $200 now, I think it's worth getting if you're excited about the lineup announced.
That's just my first impressions based off the press conferences. There's a lot I still need to read about outside of those, but this year looks like it has a pretty impressive list of games from everyone.